tacoma 3rd cylinder intermittent cold misfire rough idle

Tough diagnosis/please help: My 4cylinder 2.7L 2WD 2013 Tacoma has intermittent cold misfire with rough idle every 1-2 weeks. Code P0303. I've replaced plugs and 3rd coil twice and checked coil connection as well as air leaks. We've switched 3rd & 4th injectors and it still gives 3rd cylinder misfire. I've used STP fuel injection cleaner & top engine cleaner with no change. It only has 55K miles. I've replaced a bad catalytic converter & oxygen sensor a year ago. It does not run hot, it does not smoke and the coolant level remains the same. The misfire is only in the morning if the car sits for 1-2 days then it corrects and functions normally. It's been in 2 shops without an answer. Please help.

 

????? compression test room/ambient temp

leak down test .....ambient/room temp

 

Do a leak down test.

 

I just dealt with a misfire issue, cylinder 1 was scored and one of the exhaust valves was burnt. Found a small crack in the head as well.

 

fix ??

 

I went ahead and completely rebuilt my engine, full rebuild kit from LCE and a new oem head.

 

I had every issue you mentioned above. Do a compression test, check your valve clearances, if you have access to one stick a borescope in there and check it out.

 

Discussed it with the last mechanic. He said wait until it gets worse since the diagnostic tests may not find the result.

 

The Mechanic thinks its a very early small blown head gasket. He states wait and if thats the case it will get worse.

 

Don't wait for the issue to get worse and potentially cause other problems. Have another mechanic take a look and do a leak down test, that will atleast tell you if things are wrong within the combustion chamber or not.